Fistulae are abnormal communications between two epithelial-lined surfaces. While the most common fistulae are gut-to-gut fistulae, many other types of fistulae have been described in the medial literature. Gastrointestinal (GI) fistulae represent all abnormal communications that involve the alimentary tract and can be broadly divided into congenital or acquired GI fistulae. Congenital GI fistulae are embryonic in origin and include branchial, tracheoesophageal and omphalomesenteric fistulae. Acquired GI fistulae can be categorized as internal or external. Internal GI fistulae include intestinal (i.e. gut-to-gut) or extraintestinal (i.e. genitourinary) fistulae. External (also called cutaneous) GI fistulae are classified as high-output or low-output. In addition, there are Complex Acquired GI fistulae which involve an internal and external component, surgically created fistulae and GI sinus tracts, which are attached to the alimentary canal at one end but then end blindly at the other end. (Pickhardt, P. J., et al., Radiology 2002 224(1): 9-23)
Major causes of GI fistulae include inflammation (i.e. Crohn's Disease, diverticulitis, infection, cholecystitis, appendicitis, pancreatitis); surgery/iatrogenic injury; malignancy; radiation; aortic aneurysm/graft; peptic ulcer disease; trauma; ischemia; foreign bodies; and idiopathic. (Pickhardt, P. J., et al., Radiology 2002 224(1): 9-23).
Treatments for fistulae vary widely, depending upon the cause, the anatomical structures involved and the general health of the patient. In some instances surgery may be required to treat the fistula (i.e. fistulae caused by inflammation). In most instances, however, conservative medical management is considered first. Such medical management generally includes extended hospital stays and intensive medical attention aimed at maintaining fluid and electrolyte balance, providing bowel rest and nutrition support, initiating medication treatment, ensuring skin protection and containing the fistula effluent. (Pontieri-Lewis, V., Medsurg Nursing, 2005, 14(1):68-72). Consequently, conservative medical management is an expensive course of treatment.
An anastomosis is created when the two cut ends of any hollow organs are sutured or stapled together, usually to restore continuity after resection or to bypass an unresectable disease process. Anastomoses are typically performed on blood vessels (e.g. coronary artery bypass); GI tract (e.g. resections of gastrointestinal organs are followed by anastomosis to restore continuity; bariatric surgery); urinary tract (e.g. radical cystectomy); microsurgery, e.g. so-called “nerve anastomosis” (not strictly an anastomosis according to the above definition).
Fashioning an anastomosis is typically a complex and time-consuming step in a surgical operation, but almost always crucial to the outcome of the procedure.